TM 9-2320-361-20 1-19. POWER SYSTEMS OPERATION (Contd) b. Engine Oil System Operation. The engine oil system provides lubricating oil for internal engine oil system are: 1-48 engine parts. Major components of the CRANKCASE BREATHER - Vents engine crankcase. OIL FILLER CAP - Covers engine oil fill opening. OIL DIPSTICK - Indicates engine oil level. OIL PRESSURE TRANSMITTER - Sends an electrical signal indicating engine oil pressure to the oil pressure gage on instrument panel. OIL FILTERS - Filters oil of dirt and other foreign material to help ensure flow of uncontaminated oil to engine. ENGINE OIL COOLER - Removes excess heat from engine oil as coolant circulates through internal tubes of oil cooler. ENGINE OIL PAN - Reservoir for engine oil. ENGINE OIL PAN DRAINPLUG - When removed, allows lubricating oil to be drained from engine.